What's up everyone? I'm new here, just bought an 05 Grand Cherokee limited with the 5.7L Hemi. I've always been into fast cars, bikes and boats and have built a lot of them, but have never owned a Chrysler product with the ability to upgrade the drivetrain until now. I work for Chrysler as a dyno tech, so I've talked to a lot of guys at work about some things to do with the engine to get more power, but I wanted to get an idea from a lot of people of what has worked for them. Plus I work with all stock engines at work, so lots of Hemi's but all regular ones. Mopar does their own thing somewhere else.

Anyways, I was thinking of a cam and/or some exhaust. After talking to one of the engineers at work, he told me the only difference between the new engines and mine is the cam in the DS platform and the SRV active intake. And the difference is about 50HP. Sounds to me like it wouldn't be that hard to do, and I could wire the SRV to activate and de-activate with RPM at like 4500, kind of like on or off because if I was taking the engine up that high in RPM I would only be at WOT, so the valve would function normally.

What have you guys all done for more power without breaking the wallet? What exhaust sounds good and works? CAI??? What? I'm open to suggestions. Is there a sticky thread that addresses all this? I'm a newb here, so maybe I missed it. I will post pics as soon as I clean it and change the oil. I've had it for a week. I like lots!!

From what I've seen/heard, the best gains are from a new cam, custom exhaust manifold and headers, CAI, exhaust, and a tuner. The problem with this is finding the exhaust manifold and headers. You can always advance/retard the cam. CAIs and exhaust systems are numerous for our platform. Tuners are usually either the Diablosport or Superchips.

Find the custom work and you are all set! In the meantime, a tuner, CAI, and exhaust can give you 50 horses to start.

From what I've seen/heard, the best gains are from a new cam, custom exhaust manifold and headers, CAI, exhaust, and a tuner. The problem with this is finding the exhaust manifold and headers. You can always advance/retard the cam. CAIs and exhaust systems are numerous for our platform. Tuners are usually either the Diablosport or Superchips.

Find the custom work and you are all set! In the meantime, a tuner, CAI, and exhaust can give you 50 horses to start.

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Uhm, no. You can't just add up the advertised gains of all three parts and think you're gaining that.

I've got the aforementioned mods on our WK and I like the way it runs. If I were a younger man again, I'd probably do a cam swap, underdrive pulley and so forth like I did on my 4.7 truck...back when I was a teenager.

I've got the aforementioned mods on our WK and I like the way it runs. If I were a younger man again, I'd probably do a cam swap, underdrive pulley and so forth like I did on my 4.7 truck...back when I was a teenager.

I never said you had to add them up to do it. IMO, the tuner works best with a CAI. The exhaust just makes it sound pretty. We have yet to see a dyno with the tuner improvements, but it has been talked about that you'll get 30 hp (I shouldn't have said 50, my fault).

Start with the basics - get a good high flow intake such as the AFE, a Superchips programmer, and the 3" Gibson Exhaust. Those will all give you nice gains. Then after you've experienced those upgrades for awhile, you can decide if you want to take it further.

PM me if you'd like pricing or if you'd like to chat. I'm a rep for all of those items.

Thanks for your help everyone. I PM'd 90grandoneer. Kolak, thanks when I'm ready to put some parts together I'll see what you have.

I also talked to a few other guys at work today, and I didn't realize this but the new cams in our engines are phased cams so they are bigger and longer on the journals and then end where the phaser goes. But I found a Mopar cam at work and dyno history for it and the power it makes over stock on my year and engine even the WK setup. So, I may try to get something similar. I don't know yet.

I have heard of others with the 5.7 pre Eagle heads who take the top end of a 6.1 and replace everything. I do not have the details but the guy was someone at the track who had a 07 charger. He was running 11.88 in the quarter and was able to keep up with a bone stock brand new 2013 SRT8 charger.... so the mods in his case helped... I wish I had more info.... and I know there is a huge difference between a charger/ challenger and a Jeep GC.

First, welcome to the forum, Patrick. We all hope you enjoy your experiences here. Hope I can help a little here. I am sure others will provide lots of good input too. Here's my take on increasing performance and economy, using pretty much non-invasive bolt ons. There's even more potential to be had, depending on how much $$$ you want to spend.

The biggest weak spots on the 5.7 are the pistons (top ring land) and the lousy log style exhaust manifolds. Everything else is pretty efficient, but, as with most engines, there is room for improvement. When I did mine (over a period of almost 4 years) I tried to do the easy, inexpensive stuff first and also tried to do them in a somewhat logical order.......i.e. don't put a bigger cam in and still have the stock exhaust. I also did all my own work (sometimes with my son's help), so didn't have to pay any labor costs. Over this period I spent a little over $4000. I also modded my Hemi LX the same way at about the same time....for each mod. So, the bottom line is, it'll depend on how much $$$ you want to spend and how much improvement you're looking for. Personally, I was after a little more power and better fuel economy, without doing major engine teardown. For me it's a hobby and kind of a game. While just throwing a 6.1 into it would be good (and perhaps easier and cheaper), keeping the MDS was one of my main considerations. A couple things I'd stay away from on the stock 5.7 rotating assembly are forced induction and nitrous oxide. They can and are done though, but you'll be unable to glean the full benefit of either, given the weak piston ring lands. About 7-8 lbs. of forced induction and a 100 shot of nitrous is all that are somewhat safe....but not using both together. If I ever build an engine for mine, I may then consider both these options. IMO, it's hard to justify for a daily driver though.

The ultimate goal is to increase the engine's Volumetric Efficiency (VE)....the engine's breathing efficiency, to a point that delivers the results you're after. The biggest dollar expeditures will probably be the exhaust system, the cylinder heads (if you decide to do this), and the camshaft and kit. Below are some of the mods that are "suppose to" deliver positive results. Remember, not each mod by itself will necessarily deliver tremendous results, but cumulatively they all add up. Also, be aware that some mods will only deliver their benefits at wide open throttle, and may not do squat when cruising around town. Before starting I would recommend you have your PCM/TCM CALID flash files updated to the most current for your vehicle. All "guestimates" below are approximate, mostly based on advertising hype and dyno results from other forum members....mostly LX forums, since not too many WK'ers do the bigger engine mods:

--This one doesn't improve engine performance, but is probably the first thing you should do, before attempting to substantially increase engine output. I added a Sonnax Transmission Line Pressure Booster (545RFE only), which raises the transmission line pressure by up to~ 30 PSI. This increases the clutch clamping pressure and firms up the WOT shifts a bit, and hopefully increases the life of the transmission. I've had one on mine for almost 40,000 miles now and, coupled with the Superchips ATT App. makes it far superior to the stock unit.

--Cold Air Intake--about 5-15 hp., mostly at WOT. The stock airbox works fine, and is capable of processing more air than the engine is capable of ingesting. I just added a second air inlet (ask me how), used an SRT tube in place of the big honky stock sound damper unit, and a high flow filter...either a K and N or a True Flow. You can also use the Airaid Jr. intake tube, but I understand it's quite a bit more costly.

--Catch Can--IMO, an early must for any Hemi engine. Gain, unknown, but probably not a whole lot. IMO, this quote from Mike at Diablosport says it all, regarding the effectiveness of the can:

"No, this is where I comment on lost power due to oil contamination in the intake tract/combustion chamber. I will assure you that after having seen as many logs of as many HEMIs as we have here at DiabloSport, not to mention the numerous HEMI vehicles we have had on our dyno for R&D, I can say, without a doubt, that the HEMI's PCV/Oil Vapor control is the worst of anything we deal with. All you have to do is pull your intake manifold to see the puddles of oil collected in there, and realize that it eventually gets in the combustion chamber, and oil don't like to burn, thus, detonation occurs. There is no gimmick here. HEMI's have KR issues. The KR issues are 99% of the time contributed to by oil contamination in the intake charge, reducing the effective octane in the combustion chamber, and leading to a loss of performance. Plenty of people have seen solid power gains on even stock vehicles when getting rid of an oil issue by adding a catch can that works properly."

--Superchips Tuner--I have both the Superchips, with the Advanced Transmission Tuning Application (ATT), and the Diablosport Predator. Each has their benefits and are similar in a lot of respects. IMO, overall (for the 4.7 and 5.7's) the SC, with the ATT App, is superior mostly because of this App. With it you're able to pretty much "fix" the crappy shift schedules and torque management issues, whether you're keeping it stock or increasing performance. IMO, this should be done early on also. See the SC website for estimated gains.

--Complete header back exhaust system--IMO, replacing the inferior exhaust logs on the 5.7 is an absolute must. This can be one of the most expensive, and best mods you do to increase performance and VE. Whether you go with the 5.7 LX logs, the 6.1 headers, or custom headers, you'll be way ahead of anything the stock logs can deliver. There are numerous threads here that outline the "how to's" for doing this mod. Below are the two I submitted, based on my observations and experiences. On the 5.7, my exhaust guy (many, many years of custom exhaust building) said to go with a single 3 in. straight through system from front to back. He also said the catalytic converters are already high flow, and there was no need to change them. Some sort of resonator is a must if you want to stay away from the dreaded "MDS drone." Mine has very little note change whether in MDS mode or out. A system like this should be worth anywhere from 25-35 horsepower, depending on how it's done. It is a mod that you will, once installed, actually feel a significant difference, both in performance and economy.http://www.jeepforum.com/forum/f67/h...-hemi-1161475/http://www.jeepforum.com/forum/f67/b...-7-wk-1174042/

--Higher lift, longer duration cam that retains MDS, with 6.1 or 6.1 type valve train--This mod only cost me about $800 per vehicle, and delivered the biggest improvement of any mod. Competition Cams (Comp Cams) has a few MDS friendly cams that are not too radical and do not affect driveability. My "Sidewinder" cams were ground by Comp. Cams, but are Frank's Racing (FRI Engineering) custom grinds that have been dyno proven on LX vehicles over the past 7-10 years to deliver a solid 50 hp. when used with a good exhaust and intake. In addition to 6.1 valve springs and pushrods, I also added a 6.1 timing chain tensioner, and advanced the cam in the WK by 2 (total of 6) degrees. I advanced the one in my LX by 6 (total of 10) degrees to move the torque curves to a lower RPM. I used a Crower cam advance kit. I also did the complete jobs without removing the cylinder heads, but this required a modified Crane Cam's "heads on" valve spring compressor.

--Ported and/or big valve, milled cylinder heads--I didn't do this mod, due to the need for further engine tear down.... pulling the heads, and also the high approximate dollar per horsepower gained. This is probably one of the most costly mods (without complete engine teardown), and does not deliver the best bang for the buck. A pair CNC ported heads, milled .030 in. (raises compression ratio by ~1/2 point) is said to be worth only about 30 hp and can run in the neighborhood of $2000+ in addition to a refundable core charge. If I ever have to pull the heads on mine, I'd probably go with the 6.1 big valve ones or late model Eagle heads. For me, this would require changing my header flanges to match the bigger heads.

--Eagle intake manifold--This intake manifold is said to actually lose a little power on a relatively stock/slightly modified early 5.7 engine. I would only do this mod in conjunction with my current mods and with bigger heads installed. Again, Mopar Magazine did dyno tests on several intake manifolds and found that on slightly modified 5.7 Hemi's, the stock WK/LX intake works the best, followed by the Eagle unit, when used with a more heavily modded engine.

--Underdrive crankshaft pulley--The smaller pulley diameter (25% in my case) reduces the drive force required to turn the engine accessories. Manufacturers claim a 10-15 hp. increase, but you couldn't prove it by me. I think this is one that may help when coupled with other "questional benefit" mods. Mopar Magazine did a test on them and claimed they actually did increase power slightly.

--Ported or larger throttle body--This mod, while said to make some improvement, probably won't deliver noticeable gains, except maybe at wide open throttle, and only after other VE increasing mods have been done. Going from the stock 80mm TB to a BBK true 85mm unit didn't seem to do anything for me, except maybe at the race track. But then again, I didn't get to go after the install, so I'll have to wait until next spring to find out for sure. Most of the advertisements claim around a 10 hp increase. Before doing this one, understand that Chrysler uses the same 80mm TB on all of their 5.7, 6.1 and 6.4 Hemi engines, so it must be quite adequate. Some people claim better throttle response with the larger one, but usually a smaller TB will give better throttle response. As I said, I noticed no difference at all when cruising around town. IMO, if you do this one, only do it after you've made significant mods that have increased the VE.

--Sultans of Spark (SOS) ignition coils--I did this one, because it was easy to do, and allowed me to open the spark plug gaps up to .060-.065 in., which is suppose to allow for more complete burning of the fuel in the combustion chambers. So far, the thing that I noticed most was an even better idle quality than I had before. Mine always idled nicely, but it does seem to be even smoother now, and the idle RPM is more stable.

For me, I've just about run out to things to do, without getting into major engine work. I am happy with the results, have gained nearly 100 rwhp, and it now performs about as well as a stock WK SRT, and still has MDS. If you're going to do significant mods, I would highly recommend you also do some suspension work, so it'll handle better than the stock WK. I love to drive mine now, more than ever, and it's hard to believe it's the same vehicle I started with about 4 years ago.

I have a custom tune, K&N intake, magnaflow cat-back, Fastman 81mm, and a couple other things.

I didn't see anything more than MAYBE a 20-25 horse gain. Sure it's loud, and the AWD still helps me rip off the line. But unless you do what 90grand did, you won't see any huge gains.

These LOGS for exhaust manifolds are a huge restrictor on this engine IMO, and finding a set of LX/SRT headers isn't such an easy task. Let alone the cost of custom. Most guys who modify this engine see noticeable gains on headers/exhaust more than anything else.

All of these things are why I find myself looking at SRT's. I wish I could build mine into something like 90's or to my liking, but in my situation, i've always wanted an SRT and will be following that plan.

Shafer57, yes, this is a real dilemma. The earlier SRT's don't have MDS which, for me, is important and one of the big reasons my fuel economy has increased as much as it has. The later SRT's I understand have MDS, but are also even heavier than our older ones. When I bought mine for $18K a little over 4 years ago, I figured I could sink some $$$ into it without getting hurt. Also, if I like a vehicle (and I like the WK....it's more fun to drive than my LX), I'll probably keep it until the wheels fall off. At some point I'd really like to get a 6.1 engine core, rebuild it my way (over square, same or similar cam, MDS, big heads, etc.) and see if I could pull even more power and economy out of it. I haven't done a complete engine in years, but have a pretty good understanding of how far to go in performance gains without adversely affecting fuel economy. I honestly think that, if done correctly, 28-30 mpg would not be out of the question. It wouldn't be cheap to do though......maybe $6000-8000 for the engine, including the core.